Muddle and misapprehension are rooted in the simplistic terms of this debate. Drugs can be swallowed, sniffed, smoked or injected with a clean or HIV-infected needle. Experimentation with a drug can be a one-off event or the gateway to a lifetime's drug career. Some drugs are very addictive, others mildly so or not at all. The results of drug use can be harmless, handicapping, crippling or fatal. Drug use can damage families as well as users themselves.
What is needed in the drugs arena is a willingness to discuss how the law is best to be deployed in aid of public health in a discriminating and flexible way, rather than in a fixed dose across all problems. Tobacco has lessons to teach us here. The law is making a slow, stepwise alliance with the public health response to cigarette smoking. Measures include action against the entrepreneur who sells cigarettes to children under 16, legal enforcement of no-smoking rules in certain public areas, and the law in relation to workplace liability for passive smoking.
So let us consider the law in relation to just two drugs - cannabis and heroin. Cannabis is a drug which carries some real hazards - it invites tobacco smoking, reduces driving competence and can cause short-term mental illness. Current restrictions succeed in making it a drug used by only a minority of the population and usually only in low dosage.
Our interest should extend beyond just the letter of the law to study of the law as it is applied. As a result of flexibility in practice, possession of small quantities of cannabis for personal use is today usually dealt with by cautioning alone.
Heroin is a dangerous drug which attracts the most stringent control. Addicts experience a tenfold excess mortality risk and as a public health measure, the law successfully restricts but does not eliminate access to this dangerous drug. Furthermore, the law readily allows a safer substitute opiate (methadone) to be given to heroin addicts to address their addiction, and this is being increasingly provided by specialists and GPs.
The disadvantage of the control system with both drugs is the cost of enforcement, the negative effect of criminalisation, and the profits accruing to the black market.
However, from the health perspective the idea of blanket withdrawal of legal controls over drugs would be inimical because it would be likely to increase the number of people addicted to all manner of drugs, with severe personal health consequences, and access to drugs would be easy. Scientific evidence shows that the fact of access significantly encourages use.
Legalisation would also increase use by bringing down the price of drugs. There is ample economic research conducted in relation to alcohol and tobacco demonstrating that price powerfully determines use, and it is a myth to suppose that drug use is not influenced or deterred by price. Legalisation would encourage people who were on drugs to stay on drugs while discouraging help seeking and entry to treatment.
That leaves the question of whether legalisation might be commended not on health but economic grounds. It is pleaded that if the black market was elbowed out of this business, huge police costs would be obviated, the Mafia would go into receivership and rates for burglary would be dramatically cut. The premise on which those arguments rest are dubious when health and economic considerations are also combined.
Simplistic remedies for complex problems are dangerous medicine. It is wrong to portray current policies on drugs as having failed. What is needed is a steady nerve and further flexible development which builds on experience, rather than the pursuit of fool's gold.
Griffiths Edwards is Professor of Addiction Behaviour and John Strang is Getty Senior Lecturer at the National Addiction Centre, Institute of Psychiatry, London.